Bachmann Big Hauler Tips

The Bachmann Big Hauler is a
very popular engine, primarily because it is visually attractive
and they can be usually found real cheap. However, the Big Hauler
is intended to be a low cost mass manufactured engine and therefore
isn't built to be highly durable. This doesn't mean that the Big
Hauler is a total piece of junk. It takes a little work, but it can
be made to run long and well.

The Big Hauler has a 4-6-0 wheel configuration which is also
called a Ten Wheeler. This engine type replaced the 4-4-0 American
type in the latter half of the 19th century in fast freight and
passenger service. It was larger than the 4-4-0 and could pull a
heavier load. The 4 wheel leading truck allowed good tracking at
fairly high engine speeds. The 2-6-0 Mogul and 2-8-0 Consolidation
tended to replace the 4-4-0 in freight service.

Bachmann's model is of a generic Baldwin product. The scale of
the model is debatable. Since Ten Wheelers were built by the
thousands over several decades and in various sizes, the model
could represent a smaller narrow gauge loco in 1:20.3 scale, or a
larger loco in 1:24 scale. 10 Wheelers of the vintage modeled
didn't get big enough so that the model could reasonably represent
a prototype in 1:29 or 1:32 scale. There were larger and more
modern 10 wheelers made, but they don't look anything like this
model.

The Bachmann Big Hauler has been built in many versions over the
years. I believe that the first version was the Radio Controlled
Big Hauler which was produced in about 1990. This version was
manufactured for many years thereafter in essentially the same
form. It was never very effective as an engine, but it got many of
us started in Large Scale. R/C sets could be found at toy
discounters for as little as $50.

Either around the same time or a little later, track powered
versions appeared. Entire sets could be found at the warehouse
stores for around $100 every Christmas time. The first versions had
all plastic detail, no external valve gear, very noisy internal
gearing and sheet metal wiper style power pickups. The engines
evolved over the years slowly gaining some external metal detail,
"improved" power pickups, external valve gear, several different
internal gearing arrangements, and a variety of different external
details. The evolved engines were called the "Plus" series, but in
fact, there were many versions of the "Plus" engines. Improvements
were usually first applied to engines sold individually, but
eventually these improvements made it into engines in found in sets
as well.

As of October 2000, a new set, the Chattanooga Railroad,
appeared at Costco stores for $90. The set has a Christmas style
paint job on the engine and a couple of yellow coaches. I grabbed
one on impulse and I found that Bachmann has made some serious
improvements over the last few years. This one runs as smoothly and
quietly as any large scale loco and is clearly worth the money.
Don't expect that ALL of the Big Hauler traits have been fixed
however, you'll still have to tweak on it a little.

Derailments

One of the major complaints against the Big Hauler is the fact
that it tends to derail easily. The main culprit is the pilot
truck. You can try these things to materially improve the tendency
to derail.

Make sure that the truck moves and rotates freely. The most
common cause of problems is that the wires that connect the power
pickups on the leading truck get pinched and prevent free movement
of the truck. To handle 2' radius curves, the truck must be able to
move freely over the full width of the mounting slot. If the wires
are pinched, loosen the screws in bottom cover next to the truck
and free them.

The lead truck often needs to be lubricated to slide freely. Use
graphite lubricant on the sliding parts of the truck mount.

Do not tighten the long screw near the pilot truck too tightly.
If you do, it will deflect the bottom cover some and may bind up
the movement of the lead truck.

Check the gauge of the pilot truck wheels. If the wheels won't
slop sideways 1/16" or so you'll have to regauge them. Remove the
wheels on the leading truck by pulling them off. Cut the plastic
axle shorter by about 1/32" and reinstall the wheels. On some
locos, they are gauged too narrowly already. The symptom of too
narrow a gauge is that the wheels tend to pop up at the frog of a
turnout when they can't fit around the guardrails on both rails at
the frog. In this case, twist and pull on them a little to create a
small gap between the plastic insulator and the wheel.

Weight the
truck. My local Big 5 sporting goods store carries 1 oz lead
weights that are shaped like a flattened oval. Use epoxy or Liquid
Nails to glue 4 of these to the top of the truck. Make sure that
whatever weight that you use does not interfere with the movement
of the truck. Check especially for interference with the frame or
the cylinder heads.

Look to your track. The Big Hauler is intolerant of rapid
changes in grade. If the track drops away from the pilot truck too
rapidly, the truck may actually bottom out and just hang there.
When this happens, it is not likely that the truck will come back
down on the track. Note that added pilot truck weights may
interfere with the frame on turns if your track has vertical
gradients and the pilot truck spring gets depressed. Either relieve
the frame above the front pilot truck axle or fix your track.

Flaky Power Pickup

The Big Hauler is notorious for having flaky power pickup. The
engine is supposed to pick up power on 8 wheels, but in fact the
leading truck doesn't contribute much. This leaves four the drivers
and they get flaky too. Bachmann has made three different types of
power pickups, sheet metal wipers, spring loaded contacts and brass
wheel bushings. While the brass bushings are better than the
others, they develop problems too.

Old Style Wiper Contacts. If your engine is an
old one with strips of metal bent to make wipers, they may be
completely worn out or the glue that holds them to the side of the
frame has probably let go so that they have lost contact force.
Either way, the best bet is to scrap them and install LGB contacts.
Then add metal wheels and contacts to the tender. If the original
ones aren't actually worn out, they probably still don't touch the
wheels at the extremes of the axle play.

On the older
engines, I glue strips of styrene to the outsides of the frame
right above the axle slot to limit the side play so that the
contacts have a chance of making contact. I find that it takes
about 0.1" of shim on each side to control the axle play.

Piston Style
Contacts. If your engine has spring loaded contacts, you
still might want to shim the drivers as the contacts still don't
reach all the time. However, a better solution is to trash the
Bachmann contacts and install LGB contacts and then shim the axles.
The Bachmann contacts heat under heavy load and the spring looses
tension. On this engine, a spring actually melted the contact
housing. To entirely replace a contact, pull out the Bachmann
contact and unsolder the wire from the back. Then solder the wire
to the end of an LGB contact and then install it in the original
hole with a glob of hot glue or your favorite structural adhesive.
These contacts will last a long time and don't heat much when
loaded.

Bushing Style Contacts. The
third style of power contact uses the wheel bushings to provide a
connection to the wheels. The bushings are connected to the engine
with spring contact fingers mounted to the lower cover. The front
truck pickups are wired to these contact springs as well. The wires
to the engine body plug into the contact strips so that
disconnection or reversal of the power contacts is easy.

All is not well with this new system however. I noticed a
pronounced sensitivity to track condition after several hours of
running and a couple of disassemblies. One of the spring contacts
had become cocked slightly and it rested on an insulator on the
rear axle instead of the bushing. Further, the bushings seem to be
flakey. There is a wheel position related hesitation on both axles
when the engine is run from a Kadee wheel brush. During the
hesitation, the engine makes spitting and growling sounds which may
be related to motor thrashing while the resistance of the bushing
is changing. The engine runs completely smoothly when the brush is
used on the pilot wheels.

I isolated the problem to the bushings by connecting directly to
the bushing and the wheel. Other than using a conductive oil on the
bushings, there doesn't seem that there is much to be done. Perhaps
Bachmann will use a ball bearing on the next version as these seem
to work fine on locos from other manufacturers.

Tender
modifications. There isn't any convenient place on the
tender trucks to mount power pickups. I epoxied a 1" square piece
of styrene to the bottom of the truck to make a platform where I
could epoxy LGB contacts. Solder wires to the contacts before you
epoxy them down as the heat of soldering will soften most epoxies.
Connect the new contacts back to the engine with some sort of small
connector. You might have to rummage around a local electronics or
R/C car store to find something suitable or use the method
described in the Power
Connector Tips page.

Leading Truck. There doesn't seem to be much
that can be done to improve the pickup from the front truck except
by using conductive oil on the bearings. Make sure that the wires
are not broken.

Gearing

There are at least SIX different motor/gearing
systems in use in Big Haulers. The later versions have the motor
mounted in a metal bracket with the gearing. I don't have a 4th
generation loco, but from reports from the field this one seems to
be more robust than the earlier versions. Even so, I've still heard
of the gearing getting mangled. Engines with this gearing will have
a bulge on the bottom cover right between the rear drivers. This
bulge clears the larger gear needed on the axle so that a
reasonable reduction ratio could be achieved without intermediate
gearing. The 5th generation has an intermediate reduction gear and
a more substantial gearbox This version seems to be holding up well in real life service. The 6th generation is the "10th Anniversary Edition" (aka "Annie") version. I don't have one of these, but reports from the field indicate that it has the same gearing as the 5th generation drive, but with a 7 pole motor. The 7 pole motor allows it to run more smoothly at very low speed.

The R/C Big Hauler uses a gearing
system that is similar to the early track powered version, but it
has a smaller lower voltage motor. I refer to this gearing as the
1st generation as I believe that this was the first kind of Big
Hauler marketed.

The early
track powered version (2nd generation) uses the same gearing as the
first generation but it has a larger motor. Due to all these gears,
these make the most noise. In my limited experience the gears don't
seem to strip as much as the 3rd generation type. The version has a
large gear reduction ratio so that the motor runs fast (hence lots
of noise) but this also reduces the load on the motor itself which
tends to allow it to draw a little less current than the later
versions. This engine runs fine on the puny power pack that is
included in the Big Hauler sets. The later versions, especially the
3rd and 4th generations, tend to really tax the little power pack
as the motors on the newer units run at higher shaft torque, lower
motor speed and therefore higher motor current.

The 3rd generation version
uses a brass worm on the motor and plastic reduction gears. These
seem to the most prone to wiping out the gearing. Worm gears, when
placed under load, tend to thrust perpendicular to the motor shaft.
If the motor is not mounted firmly (see below), this thrust tries
to make the worm walk over the teeth on the meshed gear. This is
evidenced by a clear popping or clicking noise, particularly when
running loaded in reverse. This version was produced from the early
90's to about 1997 so the majority of Big Haulers out there,
including many of the "Plus" versions will have this type of
gearing.

I don't have a 4th generation Big
Hauler, but Dan Pierce sent a photo of his. This one uses a worm on
the motor and a single gear on the axle. The motor and rear axle
are held in a bracket made from a piece of sheet metal bent into a
U shape. The axle gear is fairly wide and centered on the axle.
There is a bump on the lower cover to clear this gear. The bump is
also centered.

This version should have had a lower gear failure rate, but it
didn't appear to work to well. There have been many reports of this
configuration eating its gearing under load.

The 5th version is
shown in the photo. This version appeared sometime during 2000.
This one has an intermediate reduction gear and a more substantial
metal gearbox assembly. The axle gear is narrower and offset from
the center. The bump in the lower cover is also offset from the
center.

There have been reports that this version has a tendency to
slip. The large axle gear is apparently not attached well enough to
the axle and can slip on the axle. Mine has not done this, but
those with the problem have reported that if a hole is drilled in
the plastic bushing next to the large gear and right through the
axle and the bushing on the other side and a pin is inserted, the
axle then becomes locked to the gear. The hole should be just large
enough to clear the pin. A piece of steel wire would work. Then
ends should be folded down to capture the wire.

Motor Mount Modifications

A common problem with Big Haulers is stripped gears. There are a
variety of causes, but a major one is that the motor mount is
inadequate. Other causes are heavy loads in high heat and
inadequate lubrication. I can't recommend much about operation in
high heat except maybe don't do it, but the other problems can be
fixed.

In the earlier versions, the motor is held in by two mechanisms,
neither of which is adequate. Glue holds it in place, that is until
the motor heats up and the glue lets go. Also the motor is pinched
in saddles. Unfortunately, one of the saddles is in the bottom
cover which is not very stiff. Under heavy loads, the whole bottom
cover will flex in response to motor loads and the motor squirms
around.

For those of you that have
the gearing with the brass worm and multiple reduction gears (3rd
generation), you should make this modification to the motor mounts
or you probably WILL strip some gears eventually.
The earlier versions without the brass worm don't seem to need this
modification, but it won't hurt. The 4th and 5th generations don't
seem to need this modification either.

Open both the top and bottom of the engine and wrap a long heavy
duty cable tie around the motor and the iron weight mounted on top
of the frame as shown in the photo above. Cinch that sucker down
TIGHT. This holds the motor in the frame half of
the saddles and materially improves problems with stripped gears.
This is most important on the types with a brass worm gear and
multiple nylon reduction gears.

Now that I've recommend that you cable tie the motor, you
MUST make sure that you have the new motor mount
ring. The new motor mount ring is a white plastic ring that wraps
around the motor bearing on the worm end. This part can be clearly
seen in the photo. The old type is yellowish clear plastic and is
much softer. If you cable tie the motor down with an old ring, the
ring will slowly deform and the worm will bear hard against the
first gear. This increases the load on the motor and wears the
gears and bearings out much faster. If you have an old style ring,
write Bachmann and ask for a new one, they'll send it out free.

If you already have stripped gears but the rest of the engine is
intact, send Bachmann the bad gears and they'll probably send new
ones back for free.

I've probably had better luck than many people with Big Hauler
gears because my engines lead a sheltered life. The always stay in
a cool basement which never gets warmer than 60 F. This is a far
cry from sitting on the ground in Phoenix in the summer where the
ground level temperatures can exceed 140 F. At these temperatures,
the plastic gears will soften and be much more susceptible to being
mangled.

Even so, I spun the gear on the driver axle on an old Big
Hauler. This happened after I added weight and could pull a heavier
load. It was a simple matter to repair the gear, almost in place. I
slid the gear off the knurled section of the axle and then coated
the knurling with a filled epoxy. I then slid the gear back over
the knurling to the proper position and allowed the epoxy to set.
The epoxy grabbed on the knurling and on the ripped up plastic that
had slid on the knurling and mechanically bonded the gear back on
the axle. This patch has not given me any more trouble in 8 years
of blatant abuse.

I think that one of the basic reasons for Big Haulers stripping
gears more often that other locos is that there is only one gear
train to take up the load. Other locos usually have 2 or 4 gear
trains so that the stresses placed on those gears are
proportionally less. Add this to some heat and sloppy meshing and
disaster is very likely.

The Delton C-16 had only one drive gear and it has a reputation
for stripping and wearing gears too. BBT's Bachmann conversion also
has only one gear train, but it is an industrial strength system
and doesn't seem to suffer the same difficulties.

The Radio Controlled Big Hauler

The Big Hauler was made in a R/C version. This engine looked
externally identical to an early track powered version but ran from
internal batteries and a rudimentary radio control system. The
engine was available only in train sets.

The R/C gear is a simple AM system that operates at 27 MHz
although there may have been some 49 MHz systems out there as well.
If the engine ran out of range of the transmitter, it would run at
its default setting of full forward until it came back into range.
This made backing moves difficult as the engine would try to go
forward every time it lost its RF signal which would often result
in severe bucking.

When working properly, the motor control system is very
effective. The engine can be nudged along at very low speeds and it
runs steadily, that is as long as you are close enough to the
engine to prevent it from running away.

The R/C receiver is mounted on a circuit board in the smoke box
and is a little difficult to get to. The antenna wire runs down the
left side of the engine and loops through the cab. It has to be
disconnected at a screw terminal about halfway along the left side
of the boiler before the shell can be removed.

The RF receiver circuits take up roughly the front 1/3 of the
circuit board. The H-bridge motor controller takes up the center
1/3 of the board and the sound system takes up the rearmost 1/3 of
the board. The wire leading to the tender carries the signal to the
speaker. In a track powered Big Hauler, this wire carries the
pulses from the sound switch.

The R/C Big Hauler is designed to run from 9 volts generated by
six internal D batteries. These batteries also give the engine
quite a bit of weight and with the traction tires, the engine can
pull fairly well on good batteries. However, the engine can also
flatten the batteries fairly quickly. There is an adapter cable
included to use an R/C car type sub-C rechargeable battery pack.
The voltage of the sub-C pack is typically 7.2 volts so that the
engine runs a little slower on the rechargeable battery than a good
set of alkaline batteries.

The R/C Big Hauler has another problem. Its plastic drivers are
intended to run on plastic track. After extended running on tight
radius metal track, the flanges will get roughed up and eventually,
they will generate so much traction against the rails in turns that
the outside rear driver will literally climb the rail and derail.
As much as I tried, I couldn't get the wheel resurfaced adequately
so I replaced the drivers with a metal set that was made for the
same vintage track powered Big Hauler. The gearing was identical so
it fit right on. However, the downside is that for some reason,
every time the engine ran in reverse over a turnout, some sort of
radio interference was generated and the engine tended to try to
reverse and buck. I never did fix this problem, we just had to stay
near the engine so that the radio signal was fairly strong. We did
find that by touching the transmitter antenna to the track, that
the track tended to conduct the radio signal to the engine and it
did run better.

The R/C Big Hauler was not equipped with smoke, but I found that
the smoke stacks themselves make an excellent replacement oil stack
for a Bachmann Shay. The stack needs to be filed before it will
fit, but once in place and airbrushed with a light coating of
engine black, it matches the Shay smokebox color very well. The
sound generators also transplant
into a Shay well and produce a credible chuffing sound for
considerably less investment than a digital sound system.

What To Do In Case Of Total
Devastation

If your Big Hauler is really too far gone for remedial work, you
have several options:

Toss it in your scrap box for parts.

Convert it to a stationary boiler for your engine house.

Send it back to Bachmann with $20. Under the limited lifetime
warranty, they'll do what it takes to fix it. You may get a whole
new bottom end but you'll still have a Bachmann Big Hauler.

Send your wheels and $199.99 to Barry's Big Trains in
Las Vegas. Barry will supply a totally new and bullet proof bottom
end for the engine. People that have done this rave about his work.
I've been waiting for one of mine to totally bite the dust before I
send it to him, but the damn things refuse to crap out. For a
little extra, he'll convert it to a 2-8-0. Barry can also be
reached at PO Box 93934 Las Vegas NV 98193-3534 or at (702) 260
9111 or by Email.

After market Upgrades

Barry of Barry's
Big Trains sent me a set of his new laser cut stainless steel
siderods for the Big Hauler. He makes these because the Bachmann
siderods sometimes don't fit his mechanisms due to some rather poor
tolerance control at the Bachmann factory. After looking around for
an engine to install them on, I realized that none of my engines
really needed them. I did test fit them on an R/C Big Hauler and
found that they fit fine. I put the old rods back on because it
didn't seem right to put such a nice set of hardware on an engine
that hardly runs anymore. I'm going to save them for an eventual
BBT chassis upgrade.

Barry also sent me a set of metal crosshead guides. These are
intended to replace the ones that so often break off Big Haulers. I
didn't install these either but I did overlay them on a couple of
Bachmann engines and it looks like they would fit well. Some Big
Haulers have bumps on the stock plastic guides that cause the
engine to click as it runs. These parts would fix that.

The wire between the engine and tender usually becomes very
stiff with age or in the cold and the connector can tend to pull
out in turns or it may even tip the engine or tender. This can
cause the sound to become intermittent or stop altogether or it can
cause derailments. I replace it with fine gauge speaker wire. You
can get the old contacts out of the connector shell by using a fine
point tool to depress the clips that hold the contacts into the
shell. It is easier to do it if you cut the old wire and strip off
the sleeving so that you can tug on the old wires individually. If
you don't pull the contacts out of the shell, then leave a half
inch or so of wire in the old shell and splice on a new flexible
wire.

For those of you that haven't bothered to trace it out, here is
my interpretation of the schematic of the sound generator in a Big
Hauler. This same circuit is included on the rear third of the
circuit board in an R/C Big Hauler.

Stock Bachmann Sound Board

As of sometime in 2000, Bachmann has changed the sound board.
The new circuit can be identified from the outside of the tender as
it has a volume control knob underneath the tender floor. It no
longer will blow a continuous chuff when stopped, but the chuff
profile is poor, it's decay is way too long. This can be fixed, see
Better Big Hauler Sound
for Under a Buck for more info.

The new board seems to have some leakage that will flatten the
battery over a period of a few months. If you are not going to use
it for awhile, it might be best to turn it off with the volume
control under the tender.

Smoke System

If the smoker works, but smokes weakly, it may be possible to
improve the smoke output at zero cost, see my Smoke Tips page for details. The
downside is that it may go through smoke fluid faster and be even
more likely to burn up if it runs dry.

The Bachmann smoke system tends to burn up fairly often, so if
you like smoke, you are better off replacing the smoke generator
with an LGB unit, see Smoke
Tips for a little more information on the smoke units. The Ten
Wheeler smoke generator is similar to the one in the Shay, and the same modifications can be
done.

There are a couple of differences between the Big Hauler and the
Shay. The Ten Wheeler smoke unit is fastened from the bottom so you
have remove the shell to remove the smoke generator. Also, the
stack on some units is just a little too small to accept an LGB
smoke unit so you will have to drill it out. A 3/8" drill is just
right, the smoke unit body will drop through and the lip on the top
will hold the unit right at the top of the stack. The Shay had a
conveniently placed hole in the heat sink to allow the mounting of
the regulator IC, on the Big Hauler, I had to drill a mounting
hole. Other than that, the modification is essentially the same as
for the Shay.

If your stack has a "final" on the top it may not fit properly
with an LGB smoke unit installed. it can either be discarded or
ground down to clear the lip of the LGB smoke unit.

If your Big Hauler has a funnel stack, you'll have to figure out
the mounting yourself. I don't have a funnel so I haven't worked
out the details.

This is the circuit that I
used for the Big Hauler smoke upgrade. I wired it to improve the
brightness of the headlight too. My headlight had burned out so I
replaced it with a grain-of-wheat bulb (Radio Shack 272-1092c).
This is a 12 volt bulb so it needed a 47 ohm resistor in series
with it to drop the voltage at the bulb to about 12 volts so that
it wouldn't burn up immediately. You may also need a resistor in
series with the Bachmann bulb if it burns too bright. You could
also use a 5 volt Grain-of-Wheat bulb and wire it at the output of
the regulator. You will then have to wire the smoke switch directly
in series with the smoke unit so that you can shut off the smoke
without turning off the headlight.

If your Big Hauler smoke unit is still working, you can just add
the part of the circuit to the left of the switch and your smoke
will run better at low speed with PWC. However it will also be at
more risk if you should let it run dry.

Headlight Replacement With A White LED

Bright white LEDs
(Light Emitting Diode) are available that are much brighter than
most incandescent bulbs used as large scale locomotive headlights.
This section describes changing the headlight in the circuit above
to an LED.

The Big Hauler on the left has a
Radio Shack 12v 60 mA Grain-of-Wheat bulb running at its ratings.
The Shay on the right has the stock Bachmann bulb that came on the
early production Shays, later Shays have a much more wimpy standard
yellow LED as a headlight. You can see that the Big Hauler light is
not very bright as compared to the Shay.

This photo shows the same two
engines after a bright white LED has been installed in the Big
Hauler. The LED is running at its rated 20 mA vs the 60 mA that the
old GOW bulb took. Now compare the brightness of the two locos
using the Shay as a reference to see how much brighter the white
LED is.

This is the modification
that was made to the smoke circuit above. The LED runs off
rectified track power and its current is controlled with a large
series resistor that approximates a true current source. The right
value for the voltage available is 600 ohm. I got the value by
paralleling two 1200 ohm resistors. With Aristo PWC on th track,
the LED comes on very bright before the engine even starts to
move.

The LED is
installed in place of the original lamp, but it has to face forward
to project its beam. The LED leads are insulated with shrink tube
and one lead is pressed into the original support. The support had
to be drilled out just a little to accommodate one lead and its
shrink tube. The other lead goes into the boiler just in front of
the support. A dab of hot glue holds the LED in position.

The headlight housing can just
be pulled off the loco. The LED wouldn't go into the housing until
a little gouging was done. The original hole is drilled out to 1/4"
and another 1/4" hole is drilled in front of it so that the two
holes merge together. The resultant shape is then filed out to an
oval. This allows the LED housing to slip up inside the headlight
housing.

The hard blue color of the LED can be toned down a bit by
painting the LED housing with a very thin coat of Tamiya Clear
Yellow paint. Keep the layer VERY thin, dry brushing or airbrushing
works well. The yellow paint cuts the blue color. If you use too
much the light will be distinctly yellow or even green.

Taking A Big Hauler Apart

The Big Hauler is designed to be cheap to manufacture so its
fairly easy to put together and therefore, it is easy to take
apart.

The Bottom Side

Prop the engine on two scraps of wood under the
cab roof so that it also rests on its smokestack. This prevents the
whistle and dynamo exhaust from being damaged.

The bottom cover comes off with four screws down
the center line of the bottom cover. Remove all four screws

Pry out the pilot support rods from the sides of
the smoke box.

Carefully lift off the bottom cover and place it
sideways in front of the cylinder saddle.

Put the long screw back in the middle of the
cylinder saddle so that it helps hold the saddle in place.

Do your work inside

Reassemble in the reverse order. Be very careful
not to pinch the wires to the lead truck when you reinstall the
cover. Also watch for the hook at the rear as it tends to flop to
the side and when in that position it makes getting the cover back
on difficult.

The Top Side

Pry the pilot support rods from the sides of the
smoke box

Remove two screws under the cab

Remove two screws from the sides of the boiler
near the lower center of the boiler

Remove the long screw under the cylinder
saddle

Remove four screws from under the air tanks. The
tanks will fall off.

Carefully lift the shell off. Be careful about
the wires to the smoke unit and headlight.

Do your stuff

While you're in there, glue 1 or 2 lbs of lead on
top of the cast iron weight. Note that extra weight will add
capability to pull more cars, which means that you can make the
motor work harder, which means that the motor will run hotter. If
you haven't reinforced the motor mounts, adding weight
WILL result in rapid failure of the engine.

The Chattanooga Choo Choo

Bachmann has come out with a new low cost set ($89.99 in Oct 2000
at Costco while they've got them) with a significantly upgraded
locomotive. The set has the same coaches are previous sets, the
same light duty track and the same wimpy power pack (but with no AC
output terminals). There is an engineer figure in the cab. A
fireman figure, a comic book style instruction book and a VHS video
are also included. All the wheels in the set are metal.

The new loco pulls only marginally well, but due to the new axle
bushings and improved gearing, it might be able handle increased
weight for better traction. The results of some testing can be
found on my Tractive
Effort Tests page. The engine draws less current that most
locos making it a good candidate for battery power.

The locomotive detail is improved as well. All the grab irons
are brass rod and there is a Walsharts type of valve gear
installed. The headlight is unchanged, as is the smoke unit. The
tender still has all plastic details.

The sound system in the tender has been "upgraded" too. It now
issues a timed chuff when it is triggered so that it will no longer
stop with a chuff constantly blowing. However, the decay time of
the chuff is way too long so that the chuffs tend to blend together
at high speeds. This is easily fixed, see Better Bachmann Sound for About
a Buck for instructions.

The
set comes packed with the loco, a combo coach and an observation
coach (without drumhead). Both the coaches are lighted using the
standard 9 volt battery. These coaches eat up expensive 9v
batteries fairly quickly. Since the wheels are metal and the pickup
pockets are still there, the lighting can be converted to track power
fairly easily.

A similar set is available at Sam's Club for
$99.99. I haven't seen this set (the photo was provided by Lou
Grandieri) but the Bach-man says that the set has the same new
mechanism as the Chattanooga Railroad set. The engine doesn't have
the external valve gear but the paint job is much better, less work
will be required to convert the road name and weather the loco. I
also understand that Orchard Supply Hardware has yet a third
special set for a similar cost.

The mechanism in this loco is all new, at least
to me. The troublesome wheel contact wipers and plungers are gone,
replaced with metal bushings on the axles that both pick up power
and support the locomotive. These bushings are substantially
heavier duty than the plastic bearings in former Big Haulers. The
bottom engine cover is electrically connected to the loco with two
small plugs so that the entire cover can be removed and placed
aside during loco maintenance. This also means that the power
pickups can be disconnected easily for a battery power conversion
without making any permanent modifications to the engine.

The locomotive
gearing is also substantially upgraded. It is now a two step
reduction gear system enclosed in a metal frame. The motor is also
attached to this frame so that the problems that the older locos
had with gear alignment may be solved. The gear train runs nearly
silently.

When I had the loco open for lubrication, I checked the minimum
speed. Unloaded, the drives will turn at 6 RPM at only 0.9 volts
DC. This is the lowest starting voltage that I have measured so far
on any loco. The mechanism would actually run as low as 0.7 volts,
but it would not run consistently.

This loco
had an audible tick in the valve gear, once per driver turn. I
tracked it down to a mold mark on the inside of the lower
crossguide on one side. The mark is about halfway down the length
of the crossguide, also about halfway between the crosshead and the
little sliver of plastic in the photo. The crosshead would pop over
the mark and make a click. A little careful file work removed the
mold mark and the tick.